I made one a few years back. I had an external screen that I mounted on the top of the sight. I had the button on the grip so my index finger could push it. It worked great (amazingly). It was a pain to hook up, and you really had to watch the wires. It also was not water proof because I had to remove the case on the rangfinder.I should have it around somewhere, I will try to find it and post some pics.